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Scientific Name | Oxalis natans L.f. |
Higher Classification | Dicotyledons |
Family | OXALIDACEAE |
Synonyms | Oxalis rugulosa Turcz. |
Common Names | Waterklawer (a), Watersuring (a) |
National Status |
Status and Criteria | Critically Endangered B1ab(iii,v)+2ab(iii,v) |
Assessment Date | 2012/11/26 |
Assessor(s) | L.L. Dreyer, K.C. Oberlander, B.M. Bayer, J. Zietsman & D. Raimondo |
Justification | Two small, severely fragmented subpopulations remain after >90% of known subpopulations were lost when the habitat was transformed by urban expansion on the Cape Flats and vineyard and wheat cultivation in the Swartland and around Somerset West and Stellenbosch. One subpopulation is currently declining due to habitat degradation as a result of eutrophication and invasion of alien grasses. This same subpopulation is also showing signs of inbreeding depression as a result of habitat fragmentation and has very low seed set (<5%). |
Distribution |
Endemism | South African endemic |
Provincial distribution | Western Cape |
Range | Stellenbosch to Somerset West and Elandsberg. |
Habitat and Ecology |
Major system | Freshwater |
Major habitats | Swartland Shale Renosterveld, Swartland Granite Renosterveld, Cape Flats Sand Fynbos |
Description | Seasonal pools along slow-flowing seasonal streams, 50-200 m. |
Threats |
| The majority of this species' habitat has been lost to urban expansion of the City of Cape Town and to crop cultivation in the remainder of its range. Ninety percent of recorded subpopulations are now extinct due to these two threats. This species appears to require very slow flowing water to survive. It is highly sensitive to eutrophication and changes in hydrological flow, which is suspected to have caused the local extinction of subpopulations on the Cape Flats. |
Population |
Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Oxalis natans L.f. | CR B2ab(iii) | Raimondo et al. (2009) | | Oxalis natans L.f. | Endangered | Hilton-Taylor (1996) | |
Bibliography |
Cook, C.D.K. 2004. Aquatic and wetland plants of southern Africa. Backhuys Publishers, Leiden, The Netherlands.
Goldblatt, P. and Manning, J.C. 2000. Cape Plants: A conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town.
Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.
Raimondo, D., von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. and Manyama, P.A. 2009. Red List of South African Plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
Sieben, E.J.J. 2009. The status and distribution of vascular plants (Magnoliophyta, Lycophyta, Pteridophyta). In: W.R.T. Darwall, K.G. Smith, D. Tweddle and P. Skelton (eds.), The status and distribution of freshwater biodiversity in southern Africa (pp. 83-98), IUCN and SAIAB, Gland, Switzerland and Grahamstown, South Africa.
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Citation |
| Dreyer, L.L., Oberlander, K.C., Bayer, B.M., Zietsman, J. & Raimondo, D. 2012. Oxalis natans L.f. National Assessment: Red List of South African Plants version . Accessed on 2025/04/14 |
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